The top Western-backed rebel commander in Syria has fled the country amid growing infighting with Islamist rebels, U.S. officials said Wednesday.

Gen. Salim Idris of the Free Syrian Army fled into Turkey and flew to Doha, Qatar on Sunday after Islamist rebel groups took over his headquarters and warehouses of U.S.-provided military gear along the border between Turkey and Syria, the Wall Street Journalreports.

The rise in northern Syria of the Islamic Front — a rebel alliance of groups that seek an Islamic state but insist they are not linked to al-Qaeda — prompted the U.S. and the U.K. to cut off supplies of non-lethal military aid to rebels in the region, officials said Wednesday.

The U.S. is calling for Idris to return even as it has begun direct talks with the Islamic Front to persuade some groups to join the Syria peace conference in Geneva on Jan. 22.